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Full text of "Text Book Of Mechanical Engineering"

Appendix III.

929

By plotting the efficiencies to a base of distance transmitted,
as in Fig. 885, we have  a  graphic means of determining the

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igSo
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fVtIL. KS         Tf*H MSMf TrO

. (.........I____I____L_I_____{____I____I____!____i......I...

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Eig. 885.

relative advantages of the three systems. A probable line for
the efficiency of electric transmission is also shewn. For very
long distances it cannot be approached by any of the other
methods.

A philosophical result of immense importance may be deduced
from a consideration of this diagram. In wire-rope, solid farts
are transmitted, and the efficiency falls off rapidly: hydraulics
transmit liquid parts, and the efficiency holds up better: gaseous
parts are carried in compressed air transmission, and the efficiency
is considerably raised: but the greatest success of all is obtained
by electricity, where a total efficiency of 67 % has been proved
over a distance of 118 miles. These facts shew the electric
current to be either etheric vibration or the passage of a very
attenuated fluid.